The invention relates generally to cordless telecommunications systems, and particularly to supporting TCP/IP services in a cellular radio access network connected to a telecommunications network offering TCP/IP services.
Currently under development are third generation mobile communications systems, such as the Universal Mobile Communication System (UMTS) and the Future Public Land. Mobile Telecommunication System (FPLMTS) which has later been renamed as IMT-2000 (International Mobile Telecommunication 2000). UMTS is under standardization at ETSI (European Telecommunications Standards Institute), whilst ITU (International Telecommunication Union) is standardizing the IMT-2000 system. These future systems are very similar in their basic features. In the following, the UMTS system will be dealt with in more detail.
Like all mobile communications systems, UMTS produces cordless data transmission services to mobile users. The system supports roaming, in other words, UMTS users can be reached and they can make calls anywhere, as long as they are located within the UMTS coverage area. UMTS is anticipated to satisfy a wide variety of future service needs, such as high-speed data services (multi-media), and video services, such as video calls. Many future services that will be needed are difficult to envision; therefore it is not possible to optimize UMTS to one group of services only. One conclusion from this is that UMTS must be constructed to be versatile and to permit further development. For this reason, a modular approach for the network architecture has been adopted, making it possible to implement UMTS effectively in different environments.
In the present perception, UMTS is built up of two or three carts that are illustrated in FIGS. 1 and 2: UMTS access network 1 (or UMTS base station system, UMTS-BSS) and a core network 2, 3, 4 and 5. The UMTS access network will also be generally termed a radio access network in the following. The UMTS access network 1 is mainly. responsible for things related to the radio path, i.e., it offers to the core network radio access that is needed for cordless operation. The core network 2, 3, 4 or 5 is a conventional or future telecommunications network modified to effectively utilize the UMTS access network in cordless communication. Telecommunications networks that have been contemplated as suitable core networks include the ISDN (Integrated Services Digital Network), B-ISDN (Broadband Integrated Services Digital Network), packet data networks PDN, Asynchronous Transfer Mode (ATM) networks etc., and second generation mobile communications systems, such as GSM (Global System for Mobile Communication).
Hence, the UMTS access network must be capable of providing support to various core networks, also those evolving in the future. Likewise, UMTS access networks should permit connection of various radio interfaces to the core network (narrowband, broadband, CDMA, TDMA etc.). Furthermore, the UMTS access network is typically simultaneously connected to several core networks, and hence must be capable of simultaneously supporting different core networks and their subscribers and services.
It is considered that the services of a radio access network are offered from core networks. The protocol controlling the bearer services of the radio access network should be capable of setting up through the network bearer services that would best satisfy different services in each core network. The bearer services may comprise several parameters wherewith the service quality and the efficiency of the radio network may be enhanced service-specifically.
A conceivable core network is the Transmission Control Protocol/Internet Protocol (TCP/IP) data network, the so-called Internet network. It is also possible that access to the Internet is provided through another core network, such as the General Packet Radio Service (GPRS) network. The Internet makes use of a number of TCP/IP application protocols. These include:
TELNET. This protocol enables a user terminal (or a user application program) in one machine to communicate interactively with an application process, such as a text editor running in a remote machine, as if the user terminal were directly connected to it;
FTP (File Transfer Protocol). This protocol enables a user terminal (or a user application process) to access and interact with a remote file system;
SMTP (Simple Mail Transfer Protocol). This protocol produces a network-wide mail transfer service between electronic mail systems in different machines;
SNMP (Simple Network Management Protocol). This protocol enables a user (e.g. a network management system) to collect throughput data of a network element (such as a bus or a gateway) and to control its operation through the network itself,
WWW (World Wide Web)
FIG. 3 illustrates the structure of the TCP/IP protocol. As can be seen in the figure, the application protocols are accessed through the local operating system either by a user application process or, more usually, by a user at a terminal. The application protocols, on the other hand, are connected to the IP protocol layer by means of a transport layer comprising either UDP (User Datagram Protocol) or TCP (Transmission Control Protocol). A feature common to all client-server interactions is the establishment of a traffic route between two application protocols or processes. All server application processes have an associated name which translates into a corresponding network-wide address. The translation procedure is carried out by a process known as the domain name server. The network-wide address consists of two parts: the network-wide IP address of the host in which the process is running and a local port number. The IP address is used by the IP protocol to route datagrams across the Internet to the required destination host. The port number is then used by the TCP protocol within the hostxe2x80x94or UDP, if this is being usedxe2x80x94to identify the specific process within that host to which a received message should be sent. An open system will include multiple clients and servers both of different types and of the same type. All servers of the same type, however, are assigned the same system-wide port number. For example, the port numbers of the above-described application protocols are as follows: FTP 21, TELNET 23, SMTP 25, and WWW 80. When a client process initiates a call to a correspondent server process, it uses as a destination address the IP address of the host in which the server is running coupled with the appropriate well-known port number of that server. As a source address it uses the IP address of its own host together with the free (unused) port number on that host. If TCP is being used, the local TCP protocol entity will then establish a transport connection between the client and server processes (using these addresses) over which the appropriate message exchanges can take place.
In the present-day Internet network, all services are xe2x80x98best effortxe2x80x99 (xe2x80x98best tryxe2x80x99). services. This means that the applications or users are not guaranteed any given level of quality, but the operating parameters, such as the bit error rate (BER) or delay, vary according the instantaneous degree of utilization of the Internet. Many applications, however, have clearly different optimum operating parameters. For example in a Telnet session the essential factor is the end-to-end delay, whereas in an FTP session the mean bit rate is decisive. In FTP it is insignificant if the delay experienced by individual packets is relatively long, as long as the mean bit rate remains adequate. In a Telnet session, on the other hand, the bit rate is very low, but the delay experienced by individual packets is the critical factor for the quality of the user service. Hence, the requirements placed by the different applications of Internet differ to some extent.
It is an object of the present invention to provide the best suitable bearer service for TCP/IP services in a radio access network from the point of view of the radio access network and the supported TCP/IP service.
This is achieved with a method for setting bearer service parameters for a radio network in a radio access network connected to a core network which is an IP/TCP network or offers a connection to an IP/TCP network, the method comprising the steps of receiving to the boundary of the radio access network a first IP packet relating to a given connection and reserving a bearer service for the connection in the radio access network. The method is characterized by
identifying the TCP/IP service to which the IP packet relates on the basis of the content of the IP packet,
maintaining in the radio access network information on the bearer service parameters required by each TCP/IP service,
setting the bearer service parameters in accordance with the identified TCP/IP service in the radio access network.
The invention also relates to an arrangement for setting bearer service parameters in a cellular radio access network connected to a core network which is an IP/TCP network or offers a connection to an IP/TCP network, the arrangement comprising resource control means for the radio access network by means of which bearer services are reserved for the connections, and first means located at the boundary of the radio access network, initiating reservation of a bearer service for a given connection upon receipt of a first IP packet relating to the connection. The arrangement is characterized in that it further comprises
second means maintaining information on the bearer service parameters required by each TCP/IP service in the radio access network,
said first means being adapted to identify the TCP/IP service on the basis of the content of the IP packet received from the core network and requesting from the resource control means a bearer service having the bearer service parameters required by the identified TCP/IP service, obtained from the second means.
The basic idea of the invention is that the bearer service parameters required by different TCP/IP services are predetermined in the radio access network, the correct parameters for a given connection being selected by identifying the TCP/IP service on the basis of the content of the first IP packet received. In this way, different TCP/IP services can be handled in different ways in the radio access network and a bearer service that best corresponds to the actual needs can be established through the radio access network. This avoids any collapse in service quality that the user might experience when data is transferred through the radio access network, as can happen if all services are given the same treatment. By means of the invention, not only can service quality as experienced by the user be improved, but optimization of the capacity of the radio access network is also enabled when only correct-type capacity is reserved for each connection.
In the primary embodiment of the invention, the TCP/IP service is identified on the basis of the port number in the destination port field in the TCP or UDP packet in the user data field of the IP packet. The service quality required by the TCP/IP service can also be interpreted from the protocol field of the IP packet, which indicates whether the overlaying transport protocol is TCP or UDP, for instance. Since the protocols of the different transport layers may have completely different requirements, this information can be used for setting the bearer service parameters in the radio access network. The service type field of the IP packet may also be used in the same way. Furthermore, the different subscription-specific conditions in the radio access network can be taken into account in setting the bearer service parameters. An upper limit for the bit rate or price may be defined for the subscriber, for instance.
The identifying and selection of bearer service parameters on the border of the radio access network may be carried out at the mobile station when a mobile originated connection (call) is concerned, and in the boundary region of the core network and the radio access network when a mobile terminated connection (call) is concerned.